services/keep-web/cache.go

   1 // Copyright (C) The Arvados Authors. All rights reserved.
   2 //
   3 // SPDX-License-Identifier: AGPL-3.0
   4
   5 package main
   6
   7 import (
   8         "sync"
   9         "time"
  10
  11         "git.arvados.org/arvados.git/sdk/go/arvados"
  12         "git.arvados.org/arvados.git/sdk/go/arvadosclient"
  13         "github.com/hashicorp/golang-lru"
  14         "github.com/prometheus/client_golang/prometheus"
  15 )
  16
  17 const metricsUpdateInterval = time.Second / 10
  18
  19 type cache struct {
  20         config      *arvados.WebDAVCacheConfig
  21         registry    *prometheus.Registry
  22         metrics     cacheMetrics
  23         pdhs        *lru.TwoQueueCache
  24         collections *lru.TwoQueueCache
  25         permissions *lru.TwoQueueCache
  26         setupOnce   sync.Once
  27 }
  28
  29 type cacheMetrics struct {
  30         requests          prometheus.Counter
  31         collectionBytes   prometheus.Gauge
  32         collectionEntries prometheus.Gauge
  33         collectionHits    prometheus.Counter
  34         pdhHits           prometheus.Counter
  35         permissionHits    prometheus.Counter
  36         apiCalls          prometheus.Counter
  37 }
  38
  39 func (m *cacheMetrics) setup(reg *prometheus.Registry) {
  40         m.requests = prometheus.NewCounter(prometheus.CounterOpts{
  41                 Namespace: "arvados",
  42                 Subsystem: "keepweb_collectioncache",
  43                 Name:      "requests",
  44                 Help:      "Number of targetID-to-manifest lookups handled.",
  45         })
  46         reg.MustRegister(m.requests)
  47         m.collectionHits = prometheus.NewCounter(prometheus.CounterOpts{
  48                 Namespace: "arvados",
  49                 Subsystem: "keepweb_collectioncache",
  50                 Name:      "hits",
  51                 Help:      "Number of pdh-to-manifest cache hits.",
  52         })
  53         reg.MustRegister(m.collectionHits)
  54         m.pdhHits = prometheus.NewCounter(prometheus.CounterOpts{
  55                 Namespace: "arvados",
  56                 Subsystem: "keepweb_collectioncache",
  57                 Name:      "pdh_hits",
  58                 Help:      "Number of uuid-to-pdh cache hits.",
  59         })
  60         reg.MustRegister(m.pdhHits)
  61         m.permissionHits = prometheus.NewCounter(prometheus.CounterOpts{
  62                 Namespace: "arvados",
  63                 Subsystem: "keepweb_collectioncache",
  64                 Name:      "permission_hits",
  65                 Help:      "Number of targetID-to-permission cache hits.",
  66         })
  67         reg.MustRegister(m.permissionHits)
  68         m.apiCalls = prometheus.NewCounter(prometheus.CounterOpts{
  69                 Namespace: "arvados",
  70                 Subsystem: "keepweb_collectioncache",
  71                 Name:      "api_calls",
  72                 Help:      "Number of outgoing API calls made by cache.",
  73         })
  74         reg.MustRegister(m.apiCalls)
  75         m.collectionBytes = prometheus.NewGauge(prometheus.GaugeOpts{
  76                 Namespace: "arvados",
  77                 Subsystem: "keepweb_collectioncache",
  78                 Name:      "cached_manifest_bytes",
  79                 Help:      "Total size of all manifests in cache.",
  80         })
  81         reg.MustRegister(m.collectionBytes)
  82         m.collectionEntries = prometheus.NewGauge(prometheus.GaugeOpts{
  83                 Namespace: "arvados",
  84                 Subsystem: "keepweb_collectioncache",
  85                 Name:      "cached_manifests",
  86                 Help:      "Number of manifests in cache.",
  87         })
  88         reg.MustRegister(m.collectionEntries)
  89 }
  90
  91 type cachedPDH struct {
  92         expire time.Time
  93         pdh    string
  94 }
  95
  96 type cachedCollection struct {
  97         expire     time.Time
  98         collection *arvados.Collection
  99 }
 100
 101 type cachedPermission struct {
 102         expire time.Time
 103 }
 104
 105 func (c *cache) setup() {
 106         var err error
 107         c.pdhs, err = lru.New2Q(c.config.MaxUUIDEntries)
 108         if err != nil {
 109                 panic(err)
 110         }
 111         c.collections, err = lru.New2Q(c.config.MaxCollectionEntries)
 112         if err != nil {
 113                 panic(err)
 114         }
 115         c.permissions, err = lru.New2Q(c.config.MaxPermissionEntries)
 116         if err != nil {
 117                 panic(err)
 118         }
 119
 120         reg := c.registry
 121         if reg == nil {
 122                 reg = prometheus.NewRegistry()
 123         }
 124         c.metrics.setup(reg)
 125         go func() {
 126                 for range time.Tick(metricsUpdateInterval) {
 127                         c.updateGauges()
 128                 }
 129         }()
 130 }
 131
 132 func (c *cache) updateGauges() {
 133         c.metrics.collectionBytes.Set(float64(c.collectionBytes()))
 134         c.metrics.collectionEntries.Set(float64(c.collections.Len()))
 135 }
 136
 137 var selectPDH = map[string]interface{}{
 138         "select": []string{"portable_data_hash"},
 139 }
 140
 141 // Update saves a modified version (fs) to an existing collection
 142 // (coll) and, if successful, updates the relevant cache entries so
 143 // subsequent calls to Get() reflect the modifications.
 144 func (c *cache) Update(client *arvados.Client, coll arvados.Collection, fs arvados.CollectionFileSystem) error {
 145         c.setupOnce.Do(c.setup)
 146
 147         if m, err := fs.MarshalManifest("."); err != nil || m == coll.ManifestText {
 148                 return err
 149         } else {
 150                 coll.ManifestText = m
 151         }
 152         var updated arvados.Collection
 153         defer c.pdhs.Remove(coll.UUID)
 154         err := client.RequestAndDecode(&updated, "PATCH", "arvados/v1/collections/"+coll.UUID, nil, map[string]interface{}{
 155                 "collection": map[string]string{
 156                         "manifest_text": coll.ManifestText,
 157                 },
 158         })
 159         if err == nil {
 160                 c.collections.Add(client.AuthToken+"\000"+coll.PortableDataHash, &cachedCollection{
 161                         expire:     time.Now().Add(time.Duration(c.config.TTL)),
 162                         collection: &updated,
 163                 })
 164         }
 165         return err
 166 }
 167
 168 func (c *cache) Get(arv *arvadosclient.ArvadosClient, targetID string, forceReload bool) (*arvados.Collection, error) {
 169         c.setupOnce.Do(c.setup)
 170         c.metrics.requests.Inc()
 171
 172         permOK := false
 173         permKey := arv.ApiToken + "\000" + targetID
 174         if forceReload {
 175         } else if ent, cached := c.permissions.Get(permKey); cached {
 176                 ent := ent.(*cachedPermission)
 177                 if ent.expire.Before(time.Now()) {
 178                         c.permissions.Remove(permKey)
 179                 } else {
 180                         permOK = true
 181                         c.metrics.permissionHits.Inc()
 182                 }
 183         }
 184
 185         var pdh string
 186         if arvadosclient.PDHMatch(targetID) {
 187                 pdh = targetID
 188         } else if ent, cached := c.pdhs.Get(targetID); cached {
 189                 ent := ent.(*cachedPDH)
 190                 if ent.expire.Before(time.Now()) {
 191                         c.pdhs.Remove(targetID)
 192                 } else {
 193                         pdh = ent.pdh
 194                         c.metrics.pdhHits.Inc()
 195                 }
 196         }
 197
 198         var collection *arvados.Collection
 199         if pdh != "" {
 200                 collection = c.lookupCollection(arv.ApiToken + "\000" + pdh)
 201         }
 202
 203         if collection != nil && permOK {
 204                 return collection, nil
 205         } else if collection != nil {
 206                 // Ask API for current PDH for this targetID. Most
 207                 // likely, the cached PDH is still correct; if so,
 208                 // _and_ the current token has permission, we can
 209                 // use our cached manifest.
 210                 c.metrics.apiCalls.Inc()
 211                 var current arvados.Collection
 212                 err := arv.Get("collections", targetID, selectPDH, &current)
 213                 if err != nil {
 214                         return nil, err
 215                 }
 216                 if current.PortableDataHash == pdh {
 217                         c.permissions.Add(permKey, &cachedPermission{
 218                                 expire: time.Now().Add(time.Duration(c.config.TTL)),
 219                         })
 220                         if pdh != targetID {
 221                                 c.pdhs.Add(targetID, &cachedPDH{
 222                                         expire: time.Now().Add(time.Duration(c.config.UUIDTTL)),
 223                                         pdh:    pdh,
 224                                 })
 225                         }
 226                         return collection, err
 227                 } else {
 228                         // PDH changed, but now we know we have
 229                         // permission -- and maybe we already have the
 230                         // new PDH in the cache.
 231                         if coll := c.lookupCollection(arv.ApiToken + "\000" + current.PortableDataHash); coll != nil {
 232                                 return coll, nil
 233                         }
 234                 }
 235         }
 236
 237         // Collection manifest is not cached.
 238         c.metrics.apiCalls.Inc()
 239         err := arv.Get("collections", targetID, nil, &collection)
 240         if err != nil {
 241                 return nil, err
 242         }
 243         exp := time.Now().Add(time.Duration(c.config.TTL))
 244         c.permissions.Add(permKey, &cachedPermission{
 245                 expire: exp,
 246         })
 247         c.pdhs.Add(targetID, &cachedPDH{
 248                 expire: time.Now().Add(time.Duration(c.config.UUIDTTL)),
 249                 pdh:    collection.PortableDataHash,
 250         })
 251         c.collections.Add(arv.ApiToken+"\000"+collection.PortableDataHash, &cachedCollection{
 252                 expire:     exp,
 253                 collection: collection,
 254         })
 255         if int64(len(collection.ManifestText)) > c.config.MaxCollectionBytes/int64(c.config.MaxCollectionEntries) {
 256                 go c.pruneCollections()
 257         }
 258         return collection, nil
 259 }
 260
 261 // pruneCollections checks the total bytes occupied by manifest_text
 262 // in the collection cache and removes old entries as needed to bring
 263 // the total size down to CollectionBytes. It also deletes all expired
 264 // entries.
 265 //
 266 // pruneCollections does not aim to be perfectly correct when there is
 267 // concurrent cache activity.
 268 func (c *cache) pruneCollections() {
 269         var size int64
 270         now := time.Now()
 271         keys := c.collections.Keys()
 272         entsize := make([]int, len(keys))
 273         expired := make([]bool, len(keys))
 274         for i, k := range keys {
 275                 v, ok := c.collections.Peek(k)
 276                 if !ok {
 277                         continue
 278                 }
 279                 ent := v.(*cachedCollection)
 280                 n := len(ent.collection.ManifestText)
 281                 size += int64(n)
 282                 entsize[i] = n
 283                 expired[i] = ent.expire.Before(now)
 284         }
 285         for i, k := range keys {
 286                 if expired[i] {
 287                         c.collections.Remove(k)
 288                         size -= int64(entsize[i])
 289                 }
 290         }
 291         for i, k := range keys {
 292                 if size <= c.config.MaxCollectionBytes {
 293                         break
 294                 }
 295                 if expired[i] {
 296                         // already removed this entry in the previous loop
 297                         continue
 298                 }
 299                 c.collections.Remove(k)
 300                 size -= int64(entsize[i])
 301         }
 302 }
 303
 304 // collectionBytes returns the approximate memory size of the
 305 // collection cache.
 306 func (c *cache) collectionBytes() uint64 {
 307         var size uint64
 308         for _, k := range c.collections.Keys() {
 309                 v, ok := c.collections.Peek(k)
 310                 if !ok {
 311                         continue
 312                 }
 313                 size += uint64(len(v.(*cachedCollection).collection.ManifestText))
 314         }
 315         return size
 316 }
 317
 318 func (c *cache) lookupCollection(key string) *arvados.Collection {
 319         e, cached := c.collections.Get(key)
 320         if !cached {
 321                 return nil
 322         }
 323         ent := e.(*cachedCollection)
 324         if ent.expire.Before(time.Now()) {
 325                 c.collections.Remove(key)
 326                 return nil
 327         }
 328         c.metrics.collectionHits.Inc()
 329         return ent.collection
 330 }